Releasable propeller drive



y 2, 1939- F. w. CALDWELL 2,156,750

' RELEASABLE PROPELLER DRIVE Filed Aug. 8, 1956 2 Sheets-Sheet l I IN VEN TOR.

Frank WEE/dwell ATTORNEY May 2, 1939.

F. w. CALDWELL RELEASABLE PROPELLER DRIVE Filed Aug. 8, 1936 2 Sheets-Sheet 2 I INVENTOR.. Fran/r WEE/dwell EL/W A TTORNEY Patented May 2, 1939 UNITED STATES PATENT OFFICE.

Frank w. cemweu, Hal-mm, Com, asslgnor a United Aircraft Corporation, East Hartford, I Comm, a corporathm of Delaware Application August 8, 1936, Serial No. 94,990 9 Claims. :(01. 17o- -135.e)

This invention relates to improvements in ve- It generally indicates the propeller carrying and hicle power plants, and has particular reference driving shaft of a propeller driving power plant, to improvements in the driving connection besuch as a radial internal combustion engine. It tween an engine and. a propeller driven by the is to be'understood, however, that the invention engine. a Y is not limited to the particular type of power 5 An object of the invention is to provide a drivplant used. The numeral l2 indicates theilxed ing connection between a propeller driving enfront or nose portion of the engine within which glue and a propeller driven by the engine so arthe shaeit Ill is mounted forrotation by the antiranged that a driving connection will be mainfriction bearing M.

10- tained between the engine and propeller and the .The propeller It may be of the hydraulicall 10 propeller may be permitted to overrun the enactuated controllable pitch type utilizing a hy gine at a greater speed in the same direction. draulically actuated mechanism for turning the A further objectv resides in the provision of propeller blades to low pitch against the force of manually controllable means for establishing a centrifugal action urging the blades to high l5 one-way or a two-way driving connection bepitch. Such propellers are well known to the 16 tween the engine and the propeller driven art, one example being particularly illustrated thereby. and described in Patent No. 2,032,255, issued A still further object resides in the provision February 25, 1936, to Frank W. Caldwell. The of means operatively associated with the manpropeller shaft It is driven from the engine 20 ually controllable means for automatically althrough a planetary reduction gear in which the 20 lowing the propeller to go into its high pitch planetary gears I! are mounted upon a cage l8 condition when it is free to overrun the engine. drivingly connected by suitable means, such as Other objects and advantages will be more the interengaging splines 20, to' the propeller particularly pointed out hereinafter or will beshaft Ill. The planetary gears are driven by a 26 come apparent as the description proceeds. suitable drive gear 2i operatively connected with 5 In the accompanying drawings in which like the engine crankshaft II and react against a reference numerals are used to designate similar sun gear 22. In this type of reduction gear, as parts throughout, there is illustrated a suitable long as-the sun gear is maintained against rotamechanical embodiment of what is now considtion, the planetary gears will be forcedto re- 30 ered to be the preferred form of the idea of the volve around the sun geancarrylng the cage I8 an invention. The drawings, however, are for the and thereby rotating the propeller shaft ill, but purpose of illustration only and are not to be if the sun gear is allowed to rotate in a direction taken as limiting the invention, the scope of opposite to the direction of the drive gear which which is to be measured entirely by the scope of drives the planetary gears, the motion of the the appended claims. drive gear will be taken up' by rotation of the 35 In the drawings, sun gear and the cage IE will either remain sta- Figure l is a longitudinal sectional view of a tionary or, if force be applied thereto in the right propeller driving connection constructed accorddirection, may rotate backwardly in the same ing to the idea of this invention; direction as that in which the sun gear rotates.

40 Fig. 1A is a elevational view on a reduced Conversely, if the propeller istending to drive the 40 scale of a fragmentary portion of a suitable conengine, the drive will be through the cage I 8 to trollable pitch aeronautical propeller. v the planetary gears, and the planetary gears will Fig. 2 is a transverse sectional view on the drive the drive gear connected'with the engine line 2--2 of Fig. 1; crankshaft, and the reaction to the driving force Fig. 3 is a transverse sectional view on the line of the planetary gears will be taken by the sun 45 3-3 of Fig. 1; gear 22, so that if the sun gear be allowed to ro- Fig. 4 is a transverse sectional view on the line tate freely in the same direction as that in which .44 of Fig. 1; and thepropeller is rotating, the rotation of the pro- Fig. 5 is a sectional view are fragmentary porpller may be taken up by the sun gear without t n f a m m r 8 s mila to Fig. 4 showing the rotating the maindrive gear on the engine crankvalve 60 in a different operative position; shaft. If the sun gear 22 be restrained from ro- Fig, 6 is a sectional view of'a fragmentary portation in a direction opposite to the rotation of tion of the device taken on the line 6-6 of Figthe propeller but allowed to rotate in the same ure 1. direction as that in which the propeller rotates,

as Referring to the drawings in detail, thenumeral the engine will always drive the propeller, but

2 the propeller may rotate without driving the,

engine whenever the rotational speed of the propeller is greater than that of the engine.

.With this principle in view,- a one-way clutch,

generally indicated at 24, is interposed between a flanged portion 26 of the sun gear and a fixed member 28 rigidly connected to the fixed nose piece i2 of the engine. This one-way clutch may be of any suitable construction, the form illustrated comprising a plurality of rollers 33 mounted in cam-shaped depressions provided in the flanged portion 26 of the sun gear, the cam portions being deeper at one end than at the other so that the sun gear may rotate with respect to the fixed member 28 in one direction but rotation 'in the opposite direction is prevented by the wedging of the rollers between the cam depressions in the flange portion 26 and the surrounding annular surface of the fixed member 23. As oneway or free wheeling clutches of the type indicated are well known to the art, it is, believed that a further description of such a clutch is unnecessary for the purpose of this disclosure. The clutch in this particular case is so arranged that the sun gear 22 may rotate with respect to the fixed member 28 in the same direction of rotation as that in which the engine drives the propeller i6 and is restrained against motion in the opposite direction, so that the reaction of the planetary gears is positively resisted by the sun gear and the planetary gears consequently rotate the cage l8 whenever power is being transmitted from the engine to the propeller. From the construction so far described, it will be observed that the engine will always drive the propeller when power is being transmitted from the engine to the propeller but that power will not be transmitted from the propeller to the engine, and when such a condition tends tov occur, the propeller will simply overrun the engine at a greater speed in the same direction of rotation.

A drivingconnection which permits the propeller to freely overrun the engine whenever there is a tendency for the engine speed to fall below the rotational speed of the propeller is desirable only under certain conditions, such as when, one of the engines of a multi-motored airplane fails and it is desired to decrease the drag of the rotating or windmilling propeller. Under these conditions, it has been' found that the drag of a free wheeling propeller in high pitch condition is no greater than, and in many instances may be less than, the drag of a locked feathered propeller. However, the drag of a free wheel propeller in low pitch may be greater than the drag of the propeller when connected to the engine through a two-way driving connection, and this i'actor may be made use of to provide increased drag to a multi-motored airplane, being among the more 1 specific objects of the present invention.- As it is desirable to have the propeller overrun the engine only under the particular circumstances 'mentioned above and similar circumstances which do not frequently occur in the general operation of airplanes, it is desirable that the propeller may be normally restrained from free rotation in either direction with respect to the engine. For this purpose, a manually actuatable friction clutch, generally indicated at 32, has been provided for normally restraining the sun gear 22 against rotation in either direction.

This clutch includes a pair of pressure plates 34- and 36 mounted upon a plurality of rotatable pins 38 clrcumferentially spaced around the nose piece of the engine about the axis of the shaft l0 and the sun gear 22. The pressure plate 38 has a screw threaded connection with all of the pins 33 so that upon manual rotation of the pins the pressure plate 36.can be moved toward or away from the pressure plate 34 to frictionally hold or release a clutch disk 40 which is non-rotatably attached to or formed integrally with the sun gear 22. Preferably, annular disks of friction material 42 are interposed between the pressure plates 34 and 36 and the clutch disk 40. One of the pins 38 is provided at its end projecting out of the nose piece I2 with an elongated lever member 44 to the free end of which is connected a linkage arrangement, indicated at 46, which leads to a manual control, not illustrated, placed within convenient reach of the operator of the vehicle. All otherrotatable pins 38 are provided with shorter lever members, as indicated at 43,

' and the free ends of all of these lever members are connected to an annular link by suitable means, such as the links 52, so that upon movement of the lever member 44 by the manually actuatable linkage 46 all of the pins 38 will be rotated simultaneously to move the pressure plate 36.

Normally the pins 38 are maintained to a position to hold the pressure plate 36 in engagement with the clutch disk 40 under suflicient pressure to restrain the sun gear 22 against rotation so that a two-way drive is provided between the propeller l6 and the propeller driving engine. When it becomes desirable to provide a one-way drive between the engine and the propeller, the linkage 46 is actuated to rotate the pins 33 in a direction and to an extent suflicient to release the frictional engagement between the clutch disk 40 and the pressure plates 34 and 36. Un-- der these conditions, the one-way clutch 24 will still restrain the sun gear 22 from rotation in a direction which will permit the engine to rotate without driving the propeller, but will permit the sun gear to rotate in a direction permitting the propeller to rotate without rotating the engine.

Hydraulic fluid under pressure is led to the hydraulic actuated mechanism of the propeller I through a channel 54 in the fixed member 23, which channel leads through a suitable oil collector ring 56 to apertures 53 leading to the interior of the shaft l0 through which the oil is supplied to the propeller actuating mechanism. One

of the pins 38, preferably the one to which the manually actuatable linkage 43 is connected, is provided with a valve portion 30 disposed in the fluid conduit line 54. The fixed member 23 is provided adjacent the line 54 with a drain aperture 62, and the valve 60 is effective, as particuv larly illustrated in Fig. 4, to provide a continuous channel from the line 54 in the fixed member 23 whenever the corresponding pin-33 is in a position to maintain the pressure plates 34 and 34 in frictional engagement with the clutch plate 40. Whenever-the pin is rotated to a position to release the clutch plate 40 from its frictional engagement with the pressure plates, the valve 30 is simifltaneously rotated to a position in which it ually controlling said friction clutch, and means operatively connected with said manual control means for rendering said pitch control means inoperative to change the pitch of the propeller and thereby allow said continuously urging means to increase the pitch whenever said manual control is actuated to establish a one way drive between said engine and said propeller and to restore said pitch control means to operativeness when said manual control is actuated to establish a two way drive.

8. In a controllable pitch propeller adapted to be driven by a motor, hydraulically actuated means for changing the pitch of the blades of said propeller in one direction, said blades being urged to change their pitch in the opposite direction by a force effective to move said blades when the hydraulically actuated means is ineffective, one way driving means comprising a cam and roller clutch between said motor and said propeller whereby said motor may drive said propeller and said. propeller may overrun said motor in the same direction of rotation, means comprising a manually actuatable friction clutch for normally maintaining a two way driving connection between said motor and said propeller,

and a valveassociated with said friction clutch for rendering said hydraulically actuated means ineffective when said clutch is released.

9. In combination with a propeller driving engine and. a controllable pitch propeller driven thereby, means actuatedzby hydraulic pressure for changing the pitch of said propeller in one direction, said propeller being urged to changed pitch in the opposite direction by force effective to move the propeller blades when said hydraulic pressure is rendered ineffective to change the. pitch of said propeller in said one direction, means providing a one-way or a two-way driving connection between said engine and said propeller, manually operable means for selectively changing said connection from one to the other of said'one-way and two-way driving con-. ditions, and means actuated by said manually operable means when operated to establish a one-way drive between said engine and said pr0 peller, to render said hydraulic pressure ineffective to change the pitch of said propeller for the duration of said one-way drive operation and thereby allowing the said force to change the pitch.

FRANK W. CALDWELL. 

